W 1 chapter 1 orthographic projection

Copyright ©2006 by K. Plantenberg
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Orthographic Projection
1.2) Orthographic Projection
Introduction

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Introduction
 An orthographic projection represents
different sides of an object.

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The Six Principle Views
 The 6 principle
views are
created by
looking at the
object,
straight on, in
the directions
indicated.

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Orthographic Projection
1.3) The Glass Box Method

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The Glass Box Method
 How do we create the 6 principle
views?
→ Glass Box Method:
• The object is placed in a glass box.
• The image of the object is projected on the sides
of the box.
• The box is unfolded.
• The sides of the box are the principle views.

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Glass Box Method
 The image of
the object is
projected on
the sides of the
box.

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Glass Box Method
 Things to
notice!
→ The
projection
planes.
→ The
projectors.
→ How
surfaces A
and B are
projected.

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Glass Box Method

What are the differences
between the Right Side
and Left Side views?
Top
Right Side Rear
Left Side
Bottom
They are mirror
images with one
different line
type.

What are the differences
between the Top and
Bottom, and Front and
Rear views?
Top
Right Side Rear
Left Side
Bottom
They are mirror
images with
different line types.

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Standard Views
 The standard views used in an
orthographic projection are;
→ Front view
→ Top view
→ Right side view
 The remaining 3 views usually don’t
add any new information.

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Front View
 The front view shows the most features
or characteristics of the object.
→ It usually contains the least amount of
hidden lines.
→ The front view is chosen first and the other
views are based on the orientation of the
front view.

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View Alignment
 The top and front views are aligned
vertically and share the same width
dimension.
 The front and right side views are
aligned horizontally and share the same
height dimension.

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Exercise 1-2
 Draw a visible, hidden, center and
phantom line.
Skip to next part of the exercise

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Line Types
 More on Center lines:
→ Important for interpreting cylindrical shapes.
→ Crossed center lines should be drawn at the
centers of circles.

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Line Types
 More on Center lines:
→ They are also used to indicate circle of
centers and paths of motion.

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Line Types
 Cutting Plane line:
→ Cutting plane lines are used to show where
an imaginary cut has been made through
the object in order to view interior features.
→ The line type is phantom and the line
weight is very thick (0.6 to 0.8 mm).
→ Arrows are placed at both ends of the
cutting plane line to indicate the direction of
sight.

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Exercise 1-2
 Draw a dimension/extension line and a
cutting plane line.
Skip to next part of the exercise

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Line Types
 Section line:
→ Section lines are used to show areas that
have been cut by the cutting plane.
→ Section lines are grouped in parallel line
patterns and usually drawn at a 45 angle.
→ The line type is usually continuous and the
line weight is thin (0.3 mm)

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Line Types
 Break line:
→ Break lines are used to show imaginary
breaks in objects.
→ A break line is usually made up of a series
of connecting arcs.
→ The line type is continuous and the line
weight is usually thick (0.5 – 0.6 mm).

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Exercise 1-2
 Draw a group of section lines and a break
line.
This is how section lines
might look on a drawing

Draw the center
lines in all the views.

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Creating Hidden Lines
 Rule 2:
→ Hidden lines
should always
begin and end
with a dash,
→ Exception: When
the hidden line
begins or ends at
a parallel visible
or hidden line.

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Creating Hidden Lines
 Rule 3:
→ Dashes should join at corners.

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Creating Center Lines
 Rule 1:
→ Center lines should start and end with long
dashes.

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 Rule 2:
→ Center lines should intersect by crossing
either the long dashes or the short dashes.

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 Rule 3:
→ Center lines should extend a short distance
beyond the object or feature.

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Using Phantom Lines
 Phantom lines uses:
→ They may also be used to indicate adjacent
positions of related parts.

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Using Phantom Lines
→ Used to indicate repeated detail.

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Using Phantom Lines
→ Used to indicate alternate positions of
moving parts.

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Using Break Lines
 Break lines are used to show imaginary
breaks in an object.

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Creating Break Lines
 There are two types of break lines.
→ If the distance to traverse is short the series
of connecting arcs is used.

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Creating Break Lines
 There are two types of break lines.
→ If the distance is long the thin straight line
with a jog is used.

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Line Precedence
 If two lines occur in the same place, the
line that is considered to be the least
important is omitted.
 Lines in order of precedence/importance
are as follows;
→ Cutting plane line
→ Visible line
→ Hidden line
→ Centerline

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Creating an Orthographic Projection
 Choose a front view.
→ Which view shows the most about the
object?
C

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 Decide how many views are needed.
→ How many and which views?
2
Front
Top
For procedural reasons,
we will continue this
example by drawing all
3 standard views.

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 Draw the
visible
features of
the front
view.

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 Draw
projectors
off of the
front view.

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 Draw the
top view.

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 Project
back to the
front view.

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 Draw a 45
projector
off the front
view.

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 Draw
projectors
over to the
45 line
and down.

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 Draw the
right side
view.

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 Project
back if
needed.

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 Draw
centerlines
where
necessary.

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Completed Drawing

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Projection Symbol
 United States = 3rd angle projection
 Europe = 1st angle projection

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Exercise 1-4
 Fill in the missing
lines in the front, right
side, and top views.

1 missing
visible line in
the front view.

The right side
view has 1
missing visible line
and 2 missing
hidden lines.

The top view has
5 missing visible
lines and 2
missing hidden
lines.

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Exercise 1-5
 Fill in the missing
lines in the top, front,
and right side views.

The top view has
1 missing visible
line.

The front view has
4 missing visible
lines and 4
missing center
lines.

The right side
view has 2
missing hidden
lines and 1
missing center
line.

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Exercise 1-6
 Shade in the surfaces
that will appear in the
front, top, and right
side views.
 Estimating the
distances, draw the
side views.
 Identify the surfaces
with the appropriate
letter in the
orthographic projection.

1) Shade in the
surfaces of the front
view.
2) Draw the front
view.
3) Identify the
surfaces.

1) Shade in the
surfaces of the right
side view.
2) Draw the right
side view.
3) Identify the
surfaces.
Notice the
horizontal and
vertical
projectors.

1) Shade in the
surfaces of the top
view.
2) Draw the top
view.
3) Identify the
surfaces.
Notice the 45 deg.
projector

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Exercise 1-7
 Identify the best
choice for the front
view.
 Estimating the
distances, draw the
side views.
Front view = A

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Auxiliary Views
 Auxiliary views are used to show the
true shape of features that are not
parallel to any of the principle planes of
projection. Aligned with the
angled surface
Partial
auxiliary
view
Skip advanced topic

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Exercise 1-8
 Draw the auxiliary
view for this object.

W 1 chapter 1 orthographic projection

W 1 chapter 1 orthographic projection

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W 1 chapter 1 orthographic projection